Sealing rings

ABSTRACT

This specification discloses a sealing ring particularly a piston ring for an internal combustion engine, comprising a base ring, the outer periphery of which includes a generally plane cylindrical zone, and a coating of a wear resistant material provided on said zone. In the ring disclosed, the outer peripheral surface of the coating is provided with a plurality of axially spaced circumferentially extending lands.

United States Patent lnventors Harold T. Hill;

Ronald Morris Caton, Sway, England Appl. No. 719,447 Filed Apr. 8, 1968Patented Apr. 6, 1971 Assignee Wellworthy Limited [56] References CitedFOREIGN PATENTS 67,325 4/ 1940 Czechoslovakia 277/208 930,089 7/1963Great Britain 277/235(A) 877,905 9/1942 France 277/223 PrinraryExaminer-Samuel B. Rothberg Attorney-Holcombe, Wetherill & BriseboisABSTRACT: This specification discloses a sealing ring particularly apiston ring for an internal combustion engine, comprising a base ring,the outer periphery of which includes a generally plane cylindricalzone, and a coating of a wear resistant material provided on said zone.in the ring disclosed, the outer peripheral surface of the coating isprovided with a plurality of axially spaced circumferentially extendinglands.

PATENTEDAPR 6l97| 3573874 lnvcnlar A llorney SEALING RINGS The presentinvention relates to sealing rings, and more particularly to pistonrings for internal combustion engines or compressors, theouter-peripheral or cylinder engaging surfaces of which arejcoated' orinlaid with a wear resistant material which prolongs the life of therings.

Piston rings of this type possess the disadvantage that they require anextended bedding-in period, and it has been proposed to accelerate thisbedding-in in a number of ways. One method which; has been proposed isto machine the peripheral surface of the base ring so as to form thereina plurality of lands or peaks, or a continuous helical land in the fonnof a screw thread, and then to plate the periphery with a wear resistantmaterial such as chromium, so that the resultant coating reproduces thecontours of the periphery of the base ring. During initial operation ofsuch a ring, the land or lands engage the cylinder wall and are worndown comparatively quickly, thus accelerating bedding-in.

It is an object of the present invention to provide an improved pistonring of the previously'mentioned type.

According to the present invention there is provided a sealing ring,particularly a piston ring for an internal combustion engine, comprisingabase ring, the outer periphery of which includes a generally planecylindrical zone, said zone being provided with a coating of a wearresistant material, the outer peripheral surface of which coating isprovided with a plurality of axially spaced circumferentially extendinglands or peaks.

The invention also consists in a method of manufacturing a sealing ringas previously defined, which comprises applying to a plane cylindricalouter peripheral zone of a base ring, a coating of a wear resistantmaterial, and machining or otherwise forrning the outer peripheralsurface of the coating to produce thereon a plurality of axially spacedcircumferentially extending lands or peaks.

The invention also consists in an internal combustion engineincorporating one or more sealing rings as previously defined.

By the term wear resistant material" used herein and in the claims ismeant a material having a wear resistance which is superior to that ofthe material of the base ring.

In order that the invention may be more readily understood, referencewill now be made to the accompanying drawing, in

which:

H08. 1 to 3 are transverse sections of sealing rings constructed inaccordance with various embodiments of this invention. 4

Referring to FIG. I, there is shown a sealing ring, and in particular apiston ring-for an internal combustion engine, which comprises a basering 1 formed, for example, from cast iron or steel, having acylindrical outer peripheral surface 2. This surface 2 may, as shown, bebeveled at 3. Applied to the surface 2, for example, by electroplating,is a deposit of a wear resistant material 4, such as chromium, which ismachined or otherwise formed to provide a plurality of circumferentiallyextending axially spaced, lands or peaks 5 which, during operation ofthe ring, constitute the cylinder engaging surfaces thereof.

in the embodiment shown in FIG. 2, the wear resistant material 4 isdeposited in a circumferentially extending channel 6 in the outerperipheral surface of the base ring 1. The outer peripheral surface ofthe wear resistant material 4, as well as the axial extremities of thebase ring 1 are then machined or otherwise formed to produce the peaks 5and 7 respectively.

During initial operation of the piston rings illustrated in FIGS. 1 and2, the peaks 5 and 7, since they present a comparatively small contactarea to the wall of the cylinder within which they are located, weardown comparatively rapidly, thus accelerating bedding-in. Furthermore,the grooves between the peaks serve to retain oil, which is importantwhen the rings are employed as top compression rings which generallytend to be starved of oil.

In some cases, however, these grooves tend to collect oil and pass thisoil up into the combustion chamber above the crown of the piston towhich the rings are assembled. In such applications, in order to avordthis disadvantage, the corrugated periphery of the deposit may beprovided with an overlay of a soft bearing material such as copper, tin,polytetrafluoroethylene, silver or the like. Such a construction isillustrated in FIG. 3, where the overlay is indicated at 8. This overlay8 lies in and fills the grooves between adjacent peaks 5, but due to itscomparatively soft nature does not retard bedding-in, since the peaks ofthe wear resistant material, will rapidly come into contact with thecylinder bore during initial 7 and 6 thou., whilst a petrol enginepiston ring of up to 4" diameter may have a deposit thickness of between2 and 3 thou. The peak height may be approximately one-tenth thou, and,for rings of the order of Va" in axial thickness, there may be of theorder of l0 axially spaced lands or peaks.

It will be understood that various modifications may be made withoutdeparting from the scope of the present invention. For example, althoughthe wear resistant material may be electroplated chromium, it is to beunderstood that other wear resistant materials may be employed, whichmay be applied by different techniques. For example, molybdenum,aluminum oxide, tungsten carbide or the like may be employed, and thechosen material may be applied by spraying instead of plating, forexample, by means of a flame gun or plasma spray gun. Moreover, the softoverlay 8 illustrated in FIG. 3, may also be applied to the ring shownin FIG. 1 or 2.

The lands or peaks may be separate, axially spaced peaks, or may beformed, in the manner of a screw thread around the periphery of the wearresistant coating, as a single helical peak.

We claim:

1. A piston ring for a high speed internal combustion engine, comprisinga base ring, the radially outer periphery of which includes a generallycylindrical zone defined by the locus of a straight line extendingsubstantially parallel to the ring axis and moved around a generallycircular path, the

center of which is coincident with the ring axis, and a thin' deposit ofa wear resistant material possessing a hardness greater than that of thematerial of the base ring built up in situ on said zone to an overallradial thickness between 0.002 and 0.006 inch, the outer peripheralsurface of which deposit constitutes the running surface of the sealingring, and is provided with a plurality of axially closely spacedcircumferentially ex tending lands which define therebetween a pluralityof grooves, the radial depth of which is substantially less than saidradial thickness of the deposit.

2. A sealing ring as claimed in claim 1, wherein the wear resistantdeposit is provided in a circumferentially extending channel in theouter peripheral surface of the base ring.

3. A sealing ring as claimed in claim 1, wherein an overlay of a softbearing material lies between adjacent lands of said deposit.

4. A sealing ring as claimed in claim 2, wherein the base ring is formedfrom one of the following materials, namely: cast iron and steel, andwherein said wear resistant material is selected from one of thefollowing materials, namely: chromium, molybdenum, aluminum oxide andtungsten carbide.

5. A sealing ring as claimed in claim 1 in which said deposit ischromium.

1. A piston ring for a high speed internal combustion engine, comprisinga base ring, the radially outer periphery of which includes a generallycylindrical zone defined by the locus of a straight line extendingsubstantially parallel to the ring axis and moved around a generallycircular path, the center of which is coincident with the ring axis, anda thin deposit of a wear resistant material possessing a hardnessgreater than that of the material of the base ring built up in situ onsaid zone to an overall radial thickness between 0.002 and 0.006 inch,the outer peripheral surface of which deposit constitutes the runningsurface of the sealing ring, and is provided with a plurality of axiallyclosely spaced circumferentially extEnding lands which definetherebetween a plurality of grooves, the radial depth of which issubstantially less than said radial thickness of the deposit.
 2. Asealing ring as claimed in claim 1, wherein the wear resistant depositis provided in a circumferentially extending channel in the outerperipheral surface of the base ring.
 3. A sealing ring as claimed inclaim 1, wherein an overlay of a soft bearing material lies betweenadjacent lands of said deposit.
 4. A sealing ring as claimed in claim 2,wherein the base ring is formed from one of the following materials,namely: cast iron and steel, and wherein said wear resistant material isselected from one of the following materials, namely: chromium,molybdenum, aluminum oxide and tungsten carbide.
 5. A sealing ring asclaimed in claim 1 in which said deposit is chromium.